WO2009009341A2 - Échangeur de chaleur à film tombant à efficacité améliorée - Google Patents

Échangeur de chaleur à film tombant à efficacité améliorée Download PDF

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Publication number
WO2009009341A2
WO2009009341A2 PCT/US2008/068878 US2008068878W WO2009009341A2 WO 2009009341 A2 WO2009009341 A2 WO 2009009341A2 US 2008068878 W US2008068878 W US 2008068878W WO 2009009341 A2 WO2009009341 A2 WO 2009009341A2
Authority
WO
WIPO (PCT)
Prior art keywords
insert
heat exchanger
tube
film heat
falling film
Prior art date
Application number
PCT/US2008/068878
Other languages
English (en)
Other versions
WO2009009341A3 (fr
Inventor
Charles W. Lipp
Billy G. Smith
Kam Hung Hau
William M. Boyle
Original Assignee
Dow Global Technologies Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dow Global Technologies Inc. filed Critical Dow Global Technologies Inc.
Publication of WO2009009341A2 publication Critical patent/WO2009009341A2/fr
Publication of WO2009009341A3 publication Critical patent/WO2009009341A3/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D3/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium flows in a continuous film, or trickles freely, over the conduits
    • F28D3/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium flows in a continuous film, or trickles freely, over the conduits with tubular conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D3/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium flows in a continuous film, or trickles freely, over the conduits
    • F28D3/04—Distributing arrangements

Definitions

  • the invention relates to falling-film heat exchangers. More particularly, the invention relates to an improved falling film heat exchanger that includes a spray member and an insert in the heat exchange tubes for increased heat exchange.
  • Falling-film heat exchangers are used for heating or cooling liquids such as in industrial processes.
  • exchangers are made up of an array of tubes extending between and connected at their lower and upper ends to two spaced apart tube sheets. The arrangement is surrounded by a shell.
  • the shell is provided with inlet and outlet port through which a suitable heat exchange liquid or gas can be circulated through the shell to cool or heat the feed stream flowing through the tubes. Because the retention time of the feed stream at the heat exchange surface is small and liquid inventory buildup is limited, falling-film heat exchangers are particularly well suited for feed stream materials that are sensitive to thermal history. For example, falling-film heat exchangers are particularly well suited for heating and vaporizing, or partially vaporizing, process fluids.
  • the invention provides a falling film heat exchanger.
  • the heat exchanger comprises: a shell connected to vertically spaced apart horizontally arranged upper and lower tube sheets said shell and tube sheets defining a shell side of the heat exchanger, the shell defining entry and exit ports for feeding heat exchange fluid to the shell side of the heat exchanger; a plurality of vertically positioned parallel cylindrical tubes, with each tube extending through and connected to a hole in each tube sheet; a spray member disposed for distributing a feed stream into the upper ends of the tubes; and an insert positioned in each tube for directing the feed stream to the interior walls of the tubes.
  • the invention also provides inserts for use in falling film heat exchangers.
  • the invention further provides methods for exchanging heat with a fluid stream using the heat exchangers described herein.
  • Fig. 1 is a cross-sectional representation of a falling film heat exchanger according to one embodiment of the invention.
  • Fig. 2 depicts a spray member according to one embodiment of the invention being used to distribute fluid to the upper openings of heat exchange tubes.
  • Fig. 3 depicts examples of various tube inserts.
  • Fig. 4 shows a preferred insert that is twisted and has an angled bottom edge.
  • Fig. 5 is a schematic of a setup for testing falling film heat exchangers.
  • the falling-film heat exchangers of the invention provide increased contact between the feed stream and the heat exchange surface of the exchanger, thereby increasing heat exchange efficiency with the cooling/heating fluid.
  • the heat exchangers of the invention include two important features: at least one spray member
  • Fig. 1 illustrates a simplified cross-sectional representation of a falling film heat exchanger according to one embodiment of the invention.
  • the heat exchanger 10 includes a vertical shell 20 which is joined to upper tube sheet 22 and lower tube sheet 24.
  • Shell 20 with tube sheets 22 and 24 are preferably cylindrically shaped and made of metal, although other shapes and materials may be used.
  • a plurality of vertically positioned parallel heat exchange tubes 30, 32, and 34 extend, and are connected, to vertically aligned holes 40 and 42 in the upper tube sheet 22 and the lower tube sheet 24.
  • Tubes 30, 32, 34 are preferably cylindrical and metal, but other shapes and materials may be used.
  • Fig. 1 depicts three heat exchange tubes, although the invention is not limited to three tubes and encompasses any number of tubes.
  • Vertical shell 20 defines (i.e., includes) entry 50 and exit 52 ports for feeding and removing heat exchange fluid to the shell side 54 of the exchanger. Although shown in Fig. 1 at the top of the vertical shell 20, the entry 50 and exit 52 ports may be positioned at other locations at the vertical shell 20, such as both ports being on the bottom, or one port on the top and one port on the bottom.
  • Various fluids are suitable for heat exchange, including for example gas and/or liquefied refrigerant.
  • a spray member 60 is disposed for distributing, and (as shown for illustration purposes) distributes, feed stream 62 into the upper ends of tubes 30, 32, and 34.
  • Other dispositions of spray member 60 for distributing feed stream 62 to upper ends of tubes 30, 32, and 34 are possible, including dispositions wherein spray member 60 is centered over tube 30, 32, or 34 or is instead positioned over upper tube sheet 22.
  • Feed stream 62, falling into tubes 30, 32, 34, is directed to the heat exchange surface (the inner walls) of the tubes by an insert 70, which is shown largely disposed within the upper end of tube 30. Heat is exchanged between the feed stream in the inside of tubes 30, 32, and 34 and the heat exchange fluid in the shell side of the exchanger.
  • An advantageous feature of the heat exchanger of the invention is that it is capable of providing sufficient liquid flow of feed stream to the heat exchange tubes so as to exceed the minimum liquid flow required to provide complete wetting at the tube exits.
  • This advantage is achieved by using a spray member 60 to deliver the feed stream 62.
  • Spray member 60 permits very low liquid residence times on the tube sheet.
  • Fig. 2 is a schematic depiction of a spray member 60 being used to distribute fluid to the upper openings of tubes 30, 32, and 33 and to tube sheet 22. During use of spray member 60, some of the fluid may move downwardly and other of the fluid may move simultaneously downwardly and across into the upper openings of the tubes.
  • Suitable commercial solid cone spray pattern nozzles include, but are not limited to, the Bete SC , Bete MP from Bete Fog, Inc. (Greenfield, Massachusetts, USA) and Spraying Systems FullJet spray nozzles (Wheaton, Illinois, USA).
  • the Bete MP nozzle has larger passages that are advantageous for passing particulate material in the process stream.
  • the distance between the spray nozzle discharge and the tube sheet is preferably set such that the feed stream fully covers the area of the tube-sheet where the tube openings are located.
  • Insert 70 transfers feed stream that is free-falling through the tube to the tube's wall.
  • the insert comprises a substantially an elongated body.
  • the insert is rectangular, but other geometries may be used.
  • the bottom edge of the insert is preferably angled. By “angled” it is meant that at least a portion of the bottom edge is not perpendicular to the tube in which the insert resides. Examples of angled bottom edges are shown in Fig. 3 for rectangular inserts.
  • the angle of the edge (represented by "x" in Fig. 3) is preferably between about 5 degrees and 80 degrees, more preferably 30 and 60 degrees.
  • Preferred bottom edge shapes include a wedge (Fig. 3(b)), a V-shape (Fig. 3(c)), and a half- moon or concave (Fig. 3(d)), with the wedge being more preferred.
  • the angled bottom edge directs fluid captured by the insert to the heat exchange wall of the tube.
  • the clearance between the wall and at least a portion of the bottom edge preferably the lowermost portion of the bottom edge, not exceed about 3/16 inch, preferably not exceed about 1/ 8 inch, more preferably not exceed about 1/16 inch, and even more preferably not exceed about 1/32 inch.
  • at least the lowermost point of the bottom edge contacts the tube wall.
  • the insert is positioned in the tube, preferably in the upper end of the tube.
  • Various techniques can be used for maintaining the insert in its position, including providing the insert with sufficient width such it that it lodges in the tube.
  • Other methods include configuring the top edge of the insert to suspend into the tube, for example, by providing hooks to the top edge of the insert.
  • the top edge of the insert is of a shape that permits ready suspension, such as a T-shape.
  • the insert is twisted, i.e., the top edge of the insert is rotated relative to the bottom edge.
  • the twist permits the insert to capture more free- falling feed stream and thus increases its efficiency at directing feed stream to the heat transfer surface of the tube.
  • the twist in the insert is at least about 90 degrees (i.e., 1/4 turn) and no more than about 360 degrees. Further preferably, the twist is at least about 180 degrees (i.e., 1/2 turn), and even more preferably at least about 270 degrees.
  • Fig. 4 depicts a preferred insert according to the invention having a twist of about 360 degrees.
  • the insert can be formed of various materials, but is advantageously of the same material from which the heat exchange tube, or inner portion thereof, is formed.
  • the choice of material is generally dependent on the process fluid, and includes consideration of such factors as the wettability of the surface of the material by the process fluid.
  • suitable materials include metals, plastics, and ceramics.
  • the insert be metal, and preferably stainless steel, further preferably stainless steel of about 16 gauge thickness.
  • the insert is generally of any width that allows it to fit within the heat exchange tube, provided that at least a portion of the bottom part of the insert is in close proximity to the inner surface of the tube as described above.
  • the insert is of sufficient length or shape such that free- falling fluid not contacting the wall on its way down the tube substantially contacts the insert.
  • One convenient method of selecting an insert length is to base the length on the diameter of the tube. According to this measurement, it is preferred that the insert be at least about 3 tube diameters long (e.g., if the tube is 1.5 inches in diameter, the insert is at least about 4.5 inches long), more preferably at least about 6 tube diameters long, and even more preferably, at least about 8 tube diameters long. There is no particular upper limit on the length of the insert so long as the bottom edge of the insert resides substantially within the tube. In some embodiments, a shorter insert may be advantageous if it is desired to maximize the contact time between the feed stream and the heat exchange surface of the tube.
  • a single tube system is used to demonstrate the advantages of the invention by quantifying the quantity of liquid that passes through a tube.
  • a schematic of a suitable setup is provided in Fig. 5. As shown, a 1 1/2" diameter tube 130 is fed using a commercial solid cone spray nozzle 160, resulting in approximately 2 to 3 kg per minute of liquid being fed to the tube (drop sizes at the bottom of the tube are about 2-3 mm in diameter). A weir 170 is used to remove excess liquid. A collection funnel 180 is used to collect separately the liquid that passes through the tube without contacting the walls. The flow rates are calculated from the material which contacts walls and the material that does not contact the walls. These flowrate values are used in the subsequent calculations. The inserts for this testing are fabricated from 16 gauge thickness 316 stainless steel, with each twisted unit having 360 degrees of twist as shown in Fig. 4.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

La présente invention concerne un échangeur de chaleur à film tombant amélioré qui augmente au maximum la quantité de courant d'alimentation entrant en contact avec la surface d'échange de chaleur des tubes d'échange de chaleur. L'échangeur de chaleur à film tombant comprend deux éléments importants : un élément de pulvérisation et une pièce d'insertion de tube destinée à diriger le courant d'alimentation vers la paroi du tube.
PCT/US2008/068878 2007-07-12 2008-07-01 Échangeur de chaleur à film tombant à efficacité améliorée WO2009009341A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US95922307P 2007-07-12 2007-07-12
US60/959,223 2007-07-12

Publications (2)

Publication Number Publication Date
WO2009009341A2 true WO2009009341A2 (fr) 2009-01-15
WO2009009341A3 WO2009009341A3 (fr) 2010-01-21

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2008/068878 WO2009009341A2 (fr) 2007-07-12 2008-07-01 Échangeur de chaleur à film tombant à efficacité améliorée

Country Status (1)

Country Link
WO (1) WO2009009341A2 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR623653A (fr) * 1925-11-21 1927-06-28 Guggenheim Brothers échangeur de chaleur
FR2443881A1 (fr) * 1978-12-15 1980-07-11 Snam Progetti Appareil pour distribuer un liquide sous la forme d'un film dans des tuyaux verticaux, consistant en un element cylindrique plein introduit a la maniere d'un bouchon ou obturateur
JPS60232494A (ja) * 1984-05-01 1985-11-19 Hitachi Zosen C B I Kk 膜形成部材を備えた流下液膜式熱交換器
EP0870999A2 (fr) * 1997-04-09 1998-10-14 SANYO ELECTRIC Co., Ltd. Réfrigérateur à absorption

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR623653A (fr) * 1925-11-21 1927-06-28 Guggenheim Brothers échangeur de chaleur
FR2443881A1 (fr) * 1978-12-15 1980-07-11 Snam Progetti Appareil pour distribuer un liquide sous la forme d'un film dans des tuyaux verticaux, consistant en un element cylindrique plein introduit a la maniere d'un bouchon ou obturateur
JPS60232494A (ja) * 1984-05-01 1985-11-19 Hitachi Zosen C B I Kk 膜形成部材を備えた流下液膜式熱交換器
EP0870999A2 (fr) * 1997-04-09 1998-10-14 SANYO ELECTRIC Co., Ltd. Réfrigérateur à absorption

Also Published As

Publication number Publication date
WO2009009341A3 (fr) 2010-01-21

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